how to map more than one property from array of object in javascript

You can use .map() with Object Destructuring:

let data = [
    {a:1,b:5,c:9}, {a:2,b:6,c:10},
    {a:3,b:7,c:11}, {a:4,b:8,c:12}
];
          
let result = data.map(({ a, b }) => ({a, b}));

console.log(result);
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If, as in your example, you want to exclude a particular property or few, you can use destructuring and use rest properties to create an object with only the properties you want:

var obj = [
  {a:1,b:5,c:9},
  {a:2,b:6,c:10},
  {a:3,b:7,c:11},
  {a:4,b:8,c:12}
];
const mapped = obj.map(({ c, ...rest }) => rest);
console.log(mapped);

If you want to include properties, simply extract them from the .map callback:

var obj = [
  {a:1,b:5,c:9},
  {a:2,b:6,c:10},
  {a:3,b:7,c:11},
  {a:4,b:8,c:12}
];
const mapped = obj.map(({ a, b }) => ({ a, b }));
console.log(mapped);


Use map():

var data = [
  {a:1,b:5,c:9},
  {a:2,b:6,c:10},
  {a:3,b:7,c:11},
  {a:4,b:8,c:12}
];
          
let modified = data.map(obj => ({a: obj.a, b: obj.b}))

console.log(modified);

Or if you prefer destructuring:

var data = [
    {a:1,b:5,c:9}, 
    {a:2,b:6,c:10},
    {a:3,b:7,c:11}, 
    {a:4,b:8,c:12}
];
          
let modified = data.map(({ a, b }) => ({a, b}));

console.log(modified);